The present invention relates generally to dynamic hinge sleeves and more particularly to a self-aligning dynamic hinge sleeve for self-lubricated hinge bearings.
Oil bearings and solid steel hinge sleeves are components of some typical rotors, including helicopter blade rotors. One drawback of this type of rotor is the cost of frequent scheduled and unscheduled maintenance and/or repairs. Moreover, a large percentage of rotorcraft ground time and maintenance expense is due specifically to difficulties with oil bearings, including oil leakage and bearing replacement. Thus, there exists a need for a rotor that requires less maintenance and thereby decreases costs.
One proposed solution to this problem is to replace the oil bearings with self-lubricated dynamic hinge bearings. The self-lubricated bearings are processed with long lasting, dry lubricant. These self-lubricated bearings require less unscheduled maintenance than oil bearings, which results in a lower life-cycle cost. Moreover, the self-lubricated dynamic hinge bearings can significantly reduce maintenance costs and provide a low maintenance rotor.
However, self-lubricated dynamic hinge bearings are not compatible with existing rotorcraft technology, which utilizes a solid steel hinge sleeve attached to the rotor hinge. Moreover, extensive stress testing and analysis has demonstrated that when the solid steel hinge sleeve is attached to the self-lubricating bearing dynamic hinge, the self-lubricated bearing does not typically align. As a result of this bearing misalignment, the contact stresses on the hinge bearings can peak to unacceptably high levels. This excessive load peaking can significantly reduce the life span of the self-lubricated bearing. Therefore it is necessary to reduce or eliminate load peaking if these types of bearings are to be utilized.
It is an object of the present invention to provide an improved hinge sleeve member.
It is also an object of the present invention to provide a hinge sleeve that reduces the unacceptable levels of load peaking on associated bearings.
It is another object of the present invention to provide a low maintenance rotor using self-lubricated dynamic hinge bearings thereby reducing the overall costs and maintenance of the rotor.
In accordance with the above and other objects of the present invention, a hinge sleeve for use within a rotor is disclosed. The hinge sleeve includes three cylindrical races functioning as a single unit. The inner race is surrounded by the outer race, and both the inner race and the outer race are formed of a non-elastomeric material. The middle race is positioned between the inner race and outer race and binds the races together. The middle race is elastomeric and allows the inner race and the outer race to rotate relative to each other and accommodates for misalignments during use. This mechanism attenuates the load peaking which is transmitted to the bearing material.